This invention pertains to a recording system with a gas supported record medium and more particularly to such a system characterized by means for uniformly disposing the record surface of a disc with respect to a transducer operating in cooperation therewith. This invention further particularly provides a gas supported record medium arranged and oriented in a manner to travel a path serving to subject the record surface thereof to a smoothing action in response to conjoint angular and planar changes in direction of the molecules of the disc as it is rotated.
As is known, magnetic recording surfaces of materials, such as magnetic tape material, and pliant discs made from such materials include slight surface irregularities or uneven portions. These irregularities can serve to introduce error in transducing information relative to the recording medium. Common methods used for compensating for this problem have included introduction of increased tape tension (in tape transports) and use of excessive head penetration of the record medium to reach the "valleys". The former solution is generally believed to be unavailable to a rotating disc medium while the latter greatly shortens the life of the recording surface.
According to the present invention, a magnetic record medium is arranged to be moved in a manner which serves to minimize the foregoing irregularities and unevenness and hence serves to improve the performance of the disc recording medium.
In addition, it has been observed that the rotation of a pliant record disc in closely spaced relation to an underlying smooth reference surface introduces irregular or non-uniform spacing along a given radius thereof. Such non-uniform spacing creates difficulties in providing a properly recorded signal on each of a number of concentrically oriented tracks recorded upon the medium.
Accordingly, there has been a need for an improved disc recording system employing a gas-supported record medium in which the medium is substantially uniformly spaced from an underlying reference surface throughout a predetermined lineal or radial extent.
It is further evident that there has been a need to provide a recording system of the kind described in which compensation has been made for irregularities and uneven surface portions of the recording surface. It has been observed that the underlying reference surface, such as provided herein by a large aluminum casting is required to present a very accurate reference foundation for the gas film which supports the disc. However, to manufacture the entire casting surface to such accuracy is quite costly. However, it has been observed that only the operative portion of the underlying casting requires an accurate reference surface finish.